The air pressure steel jar of a paint ball gun is connected to the bore (110) of the paint ball gun in any manner, as shown in FIG. 1; the rear end of the bore (110) disposed inside the said paint ball gun (1) connects a steel jar (2); the steel jar (2) situates inside a butt (11) and communicates with the bore (110) by means of a butt joint portion (12) of the steel jar (2) to make the bore (110) obtain air pressure as the pressure base for discharging the paint ball; however, the general application of the air pressure steel jar (2) is to recycle the steel jar (2) and refill the nitrogen, therefore, the steel jar (2) needs have an on/off valve disposed for filling the gas and conducting the in/out control in dual directions.
Referring to FIGS. 2 and 3 for the conventional parts, FIG. 2 is a drawing of a general steel jar (2) with a rotating valve (13) disposed at the butt joint portion (12); the rotating valve (13) works as the base for controlling the on/off communication between the steel jar (2) and the outside; the rotating valve (13) plugs a through hole by screwing to lock and to form a closed state; since the said rotating valve (13) is disposed in the lateral aspect of the butt joint portion (12) and, in order to obtain the effect of virtual reality, the newly made paint ball gun has the steel jar directly hidden inside the butt (11); in that case, the rotating valve (13) is unable to provide external operation, as shown in FIG. 3; therefore a resilient press lock button (14) is disposed directly on the said butt joint portion (12); the said press lock button (14) is a resilient button; when the button is pressed in, a spherical valve disposed therein is pushed away to make the inside of the steel jar (2) communicate outward so as to provide dual directional operations of filling the gas and conducting out the pressure; the press lock button (14) is disposed in a manner of utilizing the requirement of the bore (110) of the paint ball gun to have a push tenon with a convex shoulder for pressing and pushing away the said press lock button (14); however, the said assembly method utilizes the requirements of the insert joint tenon (140) disposed relatively to the outer circumference of the press lock button (14) to have tight match with the inside of the bore (110) for preventing the gas leak and reaching a tight seal with the filling nozzle for preventing the situation of gas leak; furthermore, the general paint ball gun is provided for warlike games, it is quite often that the paint ball gun will be carried and shaken; the assembly between the bore (110) and the said press lock button (14) frequently vibrates and causes gas leak at the joint area of the said valve (13); in addition, during the filling procedure, the traditional steel jar (2) may burst due to being unable to bear the inner pressure if the pressure from the pressure source is too big; therefore, the present invention has the said valve (13) designed for a convenient manual operation and to have a fuse effect.